Polarized duplex receptacle



April 10, 1934. G. E. BLINN ,9

POLARIZED DUPLEX RECEPTACLE Filed March 24. 1932 ATTORNEYS Patented Apr. 10, 1934 UNITED STATES PATENT OFFICE POLARIZED DUPLEX RECEPTACLE Application March 24, 1932, Serial No. 600,897

6 Claims.

This invention relates to receptacles used in connection with electrical wiring systems and is concerned more particularly with duplex receptacles of the three-contact type, the receptacle of the invention being so constructed that polarized connections may be made at both its ends. The new receptacle is particularly useful in connection with underfloor wiring systems and an adaptation of the invention for that purpose will 10 be described in detail in order to make the construction clear, but it is to be understood that the utility of the invention is not limited to such systems and that the new receptacle may be employed to advantage in connection with wiring systems of other types.

In underfloor wiring systems such as are now commonly used in ofiice buildings, it is desirable to provide ground wire connections, and when such ground wires are used, receptacles having 29 three terminal clips are installed in the standpipes which extend upward from the system outlets, these clips being of the usual construction and adapted to receive the prongs of a plug. Usually the clips are placed in triangular formation in the receptacle with the top clip having a terminal screw by which a ground wire can be connected to it, the ground wire leading down through the standpipe and into the ducts to some suitable ground connection. The other two terminal clips in the receptacle are then connected to the two sides of the source of energy.

If single receptacles of the three-contact type were employed throughout the system, it would be a relatively simple matter to polarize all these receptacles so that the person making a connection by inserting the plug in a receptacle could always be sure of connecting the terminals properly to the motor or other device to receive current. However, the receptacles are commonly of 40 duplex construction and have double contact clips which extend through the receptacle body in registry with openings in its opposite ends.

Heretofore, it has been the practice to attempt to polarize these receptacles, but in those constructions with which I am familiar, the contact clips in alignment in the receptacle body and registering With openings in its opposite ends have been of the same polarity. Considering the receptacle as viewed from one end, for instance, [IQ the left hand clip will be connected to the negative side of the line, the right hand clip to the positive side, and the top clip to ground. This polarizes the receptacle at one end, but viewing such a receptacle from the opposite end, it will be apparent that the left hand clip is positive,

the right hand clip negative, and the top clip grounded, by reason of the aligned clips through the receptacle being connected together. The consequence is that a receptacle thus constructed is not fully polarized. The terminals have one polarity at one end of the receptacle but the opposite polarity at the other end.

The lack of complete polarization of the terminal clips at both ends of such duplex receptacles thus renders one face of each receptacle useless when the energy supply is direct current and polarization is required. To obtain proper connections, therefore, the plug can be placed in one end only of the receptacle and not only is the other end of the receptacle useless for polarized direct current connections but in some instances represents a distinct hazard since inserting the plug in the wrong end of the receptacle may cause damage to equipment and injury to the operators, particularly when the ma- 5 chine connected is not in proper working order and is grounded.

The present invention is accordingly directed to the provision of a duplex receptacle of the three-contact type in which the terminals at both ends or faces of the receptacle are polarized so that a plug may be inserted in the openings of either face and obtain connections of the same polarity. With the new receptacle, there is no possibility of obtaining connections of reversed polarity by inserting the plug in the wrong end of the receptacle because of the complete polarization provided.

As an additional feature, the new receptacle includes an improved ground connection so that the ground prong of the plug inserted in the receptacle may be connected in the latter either to a ground wire or else directly to the receptacle housing and through the latter to the standpipe and the metallic ducts of the system. With such a ground connection, it is not necessary to use a separate ground Wire, although the new ground terminal clips in the receptacle make it possible to use either the direct ground connection to the receptacle housing, a separate ground wire, or both ground connections.

For a better understanding of the details of the invention embodied in a form suitable for use in the standpipes of underfloor duct systems, reference may be had to the accompanying drawing, in which Fig. 1 is a longitudinal section of a new duplex receptacle of this invention as seen along the line 1-1 of Fig. 2;

Fig. 2 is a cross-section thereof as seen along the line 22 of Fig. 1;

Fig. 3 is a face or end view thereof illustrating one of the receptacles;

Fig. 4 is a horizontal section as seen along the line 44 of Fig. 2;

Fig. 5 is a horizontal section as seen along the line 55 of Fig. 2;

Fig. 6 is a top view of the duplex receptacle with the housing cap removed;

Figs. 7 and 8 are perspective views of the connectors utilized to cross connect contact clips of the same polarity;

Fig. 9 is a perspective view of the insulator inserted between these connectors, and r Fig. 10 is a diagrammatic View of the connections of the contact clips of the duplex receptacle.

In the drawing, the new receptacle is iilustrated as mounted in a support 10 in the form of a metal standpipe of the type commonly used in underfloor wiring systems. The standpipe has an enlarged upper end 11 which, with a removable cap 12-, forms a housing for the receptacle, the ends of the receptacle being exposed at opposite ends of the housing.

The receptacle has flanges 13 and 14 at its ends which fit in corresponding grooves in the upper and lower parts of the housing and the receptacle includes two blocks 15 and 16 of insulating material secured together by a bolt 17, the head and nut of which lie in recesses in the faces of the blocks. Formed in the face or" the block 16 are slots 18, 19, and 21, the slots 18 and 19 being on approximately the same level and below the axis of the receptacle, while the slot 20 is above and in a vertical plane through the axis of the receptacle. The slot 18 is, therefore, commonly referred to as the left-hand slot and the slot 19 as the right-hand slot. These slots are arranged for the reception of the three prongs of a connector plug, and the block 15 is similarly provided with a left-hand slot 21, a right-hand slot 22, and an upper or center slot 23. The three slots in the two blocks lie in alignment lengthwise of the receptacle.

Seated in suitable recesses in block 16 in alignment with slots 18 and 19 are the electrical contact clips 24 and 25, respectively, as is shown in Fig. 5, and a similar contact clip 26 is mounted in block 16 in alignment with upper or center slot 20,

as shown in Fig. 1. Seated is recesses in block 15 in alignment with the slots 21 and 22 are the respective electrical contact clips 27 and 28, while contact clip 29 is seated in block 15 in alignment with center or upper slot 23.

The inner ends of the upper or center contact clips 26 and 29 in the two parts of the receptacle are secured, as by a rivet, jointly to a spring contactor 30 and a terminal 31 having the binding screw 32. The contactor 39 is so shaped that it resiliently engages and makes electrical contact with the inner surface of the cap 12 of the standpipe 10, which is grounded through the duct system. However, instead of being grounded through the standpipe 10, and duct, the contacts 26 and 29 may be directly connected to ground by means of a wire 32 connected to terminal 31 by binding screw 32 and passing downwardly through standpipe 19 to be grounded at any suitable point.

The right-hand clips 25 and 28 in the two parts of the receptacle have their inner ends secured to a cross=connector 33 which lies within a chamher formed partly in the contacting surfaces of the blocks 15 and 16. This connector 33 (Fig. 3) comprises a strip of. copper or other suitable metal and has end portions offset from one another and connected by a neck 34 of reduced size. One end portion has a terminal 35 extending from it and bent at right angles to the remainder of the connector. The contact clips 25 and 28 are connected to opposite faces of the end portions of the connector and the terminal 35 projects upwardly from between the contacting surfaces of blocks 15 and 16 and lies in a channel formed on the outer surfaces of the blocks. As illustrated in Fig. 6, the receptacle has an outer diameter substantially less than the inner diameter of the housing between its ends so that the wire 36 extending out of the duct and up through the standpipe may be connected to the terminal by the binding screw 36. With this arrangement, if the wire 36 is connected to the positive side of a direct current supply, the clips 25 and 28 have positive polarity and thus the clip in the right-hand slot in each face of the receptacle is of the same polarity.

The inner ends of the left-hand contact clips 24 and 27 are connected by a connector 37 generally similar in shape to connector 33 and comprising offset end portions connected by a neck 38, with one of the end portions having an integral terminal extension 39. The neck 38 of connector 37 is so arranged relative to the end portions that the two connectors 33 and 37 may be placed in alignment with the necks crossing but out of contact with one another. The terminal 39 of connector 3'? lies exposed in a channel formed in the outer surface or" the two parts of the receptacle and the terminal has a binding screw 40 so that a wire 49 may be attached to it. In connection with a direct current supply, wire 40' will be of opposite polarity from the wire 36 and, the contact clips 24 and 27 will be of the same polarity.

In the assembled device, the cross-connectors 33 and 3'7 extend transversely of the receptacle with their necks crossing and an insulator 41 of fibre or the like is placed between the opposed faces of the two connectors. This insulating member is slotted at 42, 43 to provide a narrow neck 44 connecting the two end portions thereof and when the member is placed between the connectors 33 and 34, the necks 34 and 38 of the two connectors enter the slots 42 and 43 so that the insulating member spaces the end portions of the two connectors and also provides an insulator for the necks thereof which cross.

The electrical connections within the receptacle are diagrammatically represented in Fig. 10 in which the clips are indicated by appropriate reference characters.

It will be seen that in the new receptacle, the clips in alignment with the left-hand slots at the opposite ends of the receptacle are of the same polarity and the clips in the right-hand slots at opposite ends of the receptacle also are of the same polarity. The clips within the top slots at each end provide a ground connection and consequently the receptacle is fully polarized and it is immaterial in which end of the receptacle the prongs or" the plug are inserted. The clips in the top slots are grounded through the standpipe and ducts and, if desired, may also be grounded by a separate ground Wire connection.-

put

' positive contacts to operators because of wrong connections can occur.

I claim:

1. In a duplex electrical receptacle, the combination of a block of insulating material having opposite faces, center and two side contacts in each face of the block, a cross-over conductor in the block, connecting the left side contacts on each face, a cross-over conductor in the block connecting the right side contacts of each face, a grounded standpip carrying the block so as to expose the opposite receptacles for use, contacting means on the block and connected to the center contacts of the receptacles and arranged to engage the standpipe to ground the said center contacts, and means on the conductors for severally connecting them to sources of positive and negative potential.

2. A duplex electrical receptacle comprising a housing, a receptacle body enclosed within said housing and made up of two sections placed end to end with their remote ends exposed at opposite ends of the housing, each section having a channel in one end surface, said channels cooperating to form an enclosed passage when said sections lie with said end surfaces in contact, three terminals mounted on said receptacle, two of said terminals being for connection to the positive and negative sides, respectively, of a source of energy and the third for connection to ground, a set of three contacts mounted in each section of said body and accessible from without the housing, two contacts of each set being of positive and negative polarity, respectively, and the third grounded, and means within the body for connecting the contacts of each set to each other and to the appropriate terminals so that the specific contacts of each set when viewed from opposite ends of the housing have the same space relation, said connecting means including a connection extending lengthwise of the body between the grounded contacts which lie in alignment and leading to said ground terminal, a pair of connections insulated from each other and extending generally transversely of said body within said passage and connecting together the two positive contacts and the two negative contacts, respectively, in the two body sections, and separate means for connecting each set of connected contacts to its terminal.

3. A duplex electrical receptacle comprising a housing, a receptacle body enclosed within the housing and made up of a pair of sections placed end to end with their remote ends exposed at opposite ends of the housing, said sections having recesses formed in their adjacent faces cooperating to form passages, three terminals mounted on the outside of said body and within said housing, two of said terminals being for connection to the positive and negative sides, respectively, of a source of energy and the third for connection to ground, a set of three contacts mounted in each section of said body and accessible from without the housing, two contacts of each set being of positive and negative polarity, respectively, and the third grounded, said positive and negative contacts in each section lying in the same relative positions when said sections are viewed from their remote ends, a connection extending lengthwise within the body and connecting the aligned grounded contacts to said ground terminal, two connections each extending generally transversely of said body within one of said passages and connecting together the two and the two negative contacts,

respectively, in the two body sections, and separate means each within one of said passages for connecting each set of connected contacts to its appropriate terminal.

4. A duplex electrical receptacle comprising a housing, a receptacle body enclosed within said housing and made up of two sections placed end to end with their remote ends extending towards opposite ends of the housing, said sections having recesses in their contacting faces cooperating to form an enclosed chamber and passages leading therefrom to the exterior of the body, three terminals mounted on said body within the housing, two of said terminals being for connec tion to the positive and negative sides, respectively, of a source of energy and the third for connection to ground, a set of three contacts mounted in each section of said body and accessible from outside the housing, two contacts of each set being of positive and negative polarity, respectively, and the third grounded, and means for connecting similar contacts of each set to the same terminal with the specific contacts of each set when viewed from opposite ends of the body having the same space relation, said connecting means including a connection extending lengthwise within said body between the aligned grounded contacts, means in one of said passages connecting said ground contact connection to the ground terminal, two connections insulated from each other and lying within said chamber, said connections extending generally transversely of said body and connecting together the two positive contacts and the two negative contacts, respectively, in the two body sections, and separate means for connecting each transverse connection to its appropriate terminal, each of said means lying in a passage.

5. A duplex electrical receptacle comprising a housing, a receptacle body enclosed within said housing consisting of two sections placed end to end with their remote ends exposed at opposite ends of the housing, said sections having recesses in their adjacent faces cooperating to form passages, three terminals mounted on said housing within the housing, two of said terminals being for connection to the positive and negative sides, respectively, of a source of energy and the third for connection to ground, a removable cap on said housing, said terminals lying beneath the cap in position to be exposed on removal of the cap, a set of three contacts mounted in each section of said body and accessible from outside the housing, two contacts of each set being of positive and negative polarity, respectively, and the third grounded, and means for connecting the contacts of each set to the appropriate terminals with the specific contacts of each set when viewed from opposite ends of the body having the same space relation, said connecting means including a connection extending lengthwise of the body between the aligned grounded contacts, means in one of said passages connecting said ground contacts to the ground terminal, two connections insulated from each other and extending generally transversely of said body within one of said passages and connecting together the two' positive contacts and the two negative contacts, respectively, in the two body sections, and separate means for connecting the sets of connected contacts to their appropriate terminals, said means each lying in one of said passages.

6. A duplex electrical receptacle comprising a housing, a receptacle body enclosed within the housing and made up of two sections lying end 4 to end with their remote ends exposed at opposite sides of the housing, said-sections having recesses in their contacting faces cooperating to form passages and said housing contacting with the body only at the remote ends of said sections to provide a substantial circumferential space around the body between it and the housing, three terminals mounted on the body within the housing and accessible at the surface of said body, two of said terminals being for connection to the positive and negative sides, respectively, of a source of energy and the third for connection to ground, a. set of three contacts mounted in each section of said body and accessible from outside the housing, two contacts of each set being of positive and negative polarity, respectively, and the third grounded and the specific contacts of each set when viewed from opposite ends of the housing having the same space relation, a connection extending lengthwise within the body'between the aligned grounded contacts, a connection within one of said passages connecting said ground contacts to the groundterminal, separate means insulated from each other and lying within one of said passages for connecting the two positive contacts and the two negative contacts, respectively, of the two body sections, and separate means each in one of said passages and connecting one of said sets of connected contacts to its terminal.

GLENN E. BLINN. 

